This invention relates to a containment device, more particularly a flexible package structure for the containment and protection of volatile substances, and most particularly to a containment device capable of providing a controllable and/or predetermined rate of ingress/egress between the ambient environment and the contents therein over a particular period of time.
Various environmental considerations make it highly desirable to control the internal atmospheric conditions within a designated area. Illustrative of those areas which are contemplated by the instant invention are the area within a room or vehicle, the area within a piece of furniture, for example in a drawer, within storage containers or storage facilities, and the like.
The type of control desired may require the release of a relatively volatile chemical agent that can function as an air freshener, an aromatizing material, an odor maskant, a pesticide, a pest repellant, an animal repellant, a herbicide, a pheromone, a disinfectant, a sterilizing agent or the like.
Alternatively, it may be desirable to expose the ambient atmosphere to a substance which has absorbtive or adsorbtive functionality. Illustrative of such substances are dessicants, odor sorbents, e.g. activated carbon, silica gel or the like. In certain contemplated embodiments, the active agent may be imbedded in a carrier and is activated by absorption of moisture from the ambient environment, whereupon the activated imbedded material is subsequently dispersed.
U.S. Pat. No. 4,145,001 discloses a package which contains plural layers wherein a quantity of a deodorizing material is sandwiched between the layers. The outer layers are taught as being impermeable to the substance and its vapors, thereby preventing escape of the vapors so long as the package is sealed. To open the package the user delaminates two selected layers such that the volatile substance is covered only on one side by a layer which is permeable to the vapors, thereby providing for a controlled release of the substance. In order to function, this patent requires an outer impermeable layer, termed a xe2x80x9crelease layerxe2x80x9d which is selected so as to form only a weak heat bond with the permeable layer. This type of seal allows the release layer to be removed without damaging the other seals. See column 2, lines 5-31. The patent discusses various useful materials among which are polyethylene, polypropylene, MYLAR polyester, foil and ethylene vinyl acetate.
U.S. Pat. No. RE. 32,513 discloses a hollow container having a partially porous shell entrapping a volatile substance and a process for dispensing said volatile substance. The container is sealed within an impermeable outer container until ready for use at which time the outer container is broken.
U.S. Pat. No. 3,815,828 provides an article for dispensing volatile material as a gas or as a vapor through an imperforate envelope. The construction is such that, over a considerable period of time, the volatile material may permeate the imperforate walls and be distributed to the surrounding atmosphere.
U.S. Pat. No. 3,896,995 provides a flying insect repellant assembly constructed to hold a relatively small pad of a liquid absorbent material which holds the insect repellant thereon. The assembly contains a pressure sensitive adhesive layer covered with a number of pliable protective sheets to protect the assembly from inadvertent contact. When the assembly is placed into use, the pliable protective sheets are removed and the adhesive film is utilized to hold the assembly in a desired location.
U.S. Pat. No. 4,094,119 teaches a method for making a volatile substance wherein a backing material, a reservoir material and a permeable material are fused together to form a composite structure which allows controlled volatilization of a substance held within the reservoir layer. At col. 5, lines 54-65, the patentee discloses the inclusion of a MYLAR polyester sheet, fused via an additional process of sonic welding to the front face to prevent volatilization prior to the time desired. Ease of removal of the MYLAR polyester layer may be controlled by the sonic welding process.
U.S. Pat. No. 4,529,125 is drawn to a volatile substance dispensing device including a reservoir layer having a first and a second side and first and second enveloping layers. The composite article is fused together in a circular shape. The use of the circular shape is deemed to be an improvement over the ""119 patent above (by the same patentee).
U.S. Pat. No. 4,419,396 describes a three-dimensional perfumed seal characterized by a vinyl base sheet, an adhesive layer on one surface of the base sheet, a release paper applied to the surface of the adhesive layer, opposite the base sheet, a foam synthetic resin padding material on the surface of the base sheet opposite the adhesive layer, a vinyl covering sheet which sandwiches the padding material in cooperation with the base sheet and having a design printed on one of the opposite surfaces thereof, and a capsulated perfume layer laminated to the covering vinyl sheet at the area where the design is present. The perfume is capsulated and requires that the capsules be rubbed or scratched to release their particular fragrance.
What is lacking in the prior art is a protective laminated package and a process for its manufacture which eliminates the requirement for a separate release layer while providing an outer protective layer which protects the contents in storage and is easily removed at the desired time of activation.
The instant invention is directed towards a package which is constructed of layers of commonly used flexible packaging materials designed to provide required protection for the contents, wherein the method of construction provides a simple easy opening of the package so the contents can provide their intended function.
Illustrative of these materials are an outer layer component such as polyester, paper, nylon, polypropylene or the like which may be laminated via an adhesive layer or an extruded layer of polyethylene to a material which functions to protect the contents of the package such as a xe2x80x9cmetalizedxe2x80x9d and/or SARAN polyvinylidene chloride or similar coated barrier films, e.g. an aluminum foil or other like material of sufficient gauge and vapor impermeability to protect the contents. Said adhesive or extrusion layer must have sufficiently high melt flow characteristics to either weld to the porous membrane and/or to flow in and around interstices of porous membranes and provide a permanent, non-peelable seal between the porous membrane and the back panel of the laminated web.
The resulting laminated composite can then be either slit into two rolls to form the front and back layers of the package, or folded in half, which is generally the preferred method since it allows for easy print registration of the front and back portions of the containment construction. If this is done, the front and the back panels can be later separated, e.g. on a horizontal form fill and seal machine by slitting a narrow strip from the folded edge.
The middle layer is a vapor permeable layer which permits communication between the ambient atmosphere and the active agent. Illustrative of materials from which this layer may be composed are porous or permeable web materials such as TYVEK spunbonded olefin, REMAY polypropylene/polyethylene or CELGARD polypropylene/polyethylene, or a roll of olefin material that has been passed over a xe2x80x9cstick rollxe2x80x9d which punches minute holes in the web, a film such as an olefin film containing a fine powder, such as a Calcium Carbonate, which has been imbedded therein to create a porous permeable film, or a thermoplastic material compatible with the front and back panels of the pouch so the required heat sealing may take place. (Dupont), REMAY or CElGARD, or a roll of olefin material that has been passed over a xe2x80x9cstick rollxe2x80x9d which punches minute holes in the web, a film such as an olefin film containing a fine powder, such as a Calcium Carbonate, which has been imbedded therein to create a porous permeable film, or a thermoplastic material compatible with the front and back panels of the pouch so the required heat sealing may take place.
Accordingly, it is an objective of the instant invention to provide a three panel pouch and a method for its construction wherein the pouch functions as a gaseous phase delivery system for materials such as perfumes, dessicants, odor maskers and odor eliminators.
It is a further objective of the instant invention to provide either a one or two station process for manufacturing the three panel pouch.
It is yet another objective of the instant invention to provide a specially formulated peelable adhesive having temperature and pressure tolerances effective to provide one peelable outer layer subsequent to heat welding of the composite structure.
It is a still further objective of the invention to provide a heat sealable composite structure wherein one outer layer is permanently sealed without the use of an adhesive layer.
An additional objective of the instant invention is provision of a compositionally modifiable heat seal composition and structure.
Yet a further objective of the instant invention is the provision of a laminate construction having an easily peelable outer layer, wherein said construction effectively controls moisture migration through the edge of the construction.